1. Field of the Invention
This invention relates to reinforcing structure for the end portions of fastener tapes in a separable slide fastener, and more particularly to a reinforcing tape or reinforcing sheet material to be attached fast to each of the end portions of fastener tapes, especially to the end portions of dyed fastener tapes, adapted for attachment thereto of a pin-and-box separator and a slide fastener provided with fastener tapes having the end portions thereof reinforced therewith.
2. Description of the Prior Art
The conventional reinforcing tapes to be applied fast to the end portions of dyed fastener tapes have included those which, for the sake of obviating the necessity of preparing reinforced tapes dyed specially in various colors matched to the colors of the aforementioned dyed fastener tapes and consequently saving such time and labor as would otherwise be incurred in the inventory control, use transparent synthetic resin films in a superposed manner so as to show the colors of the dyed fastener tapes therethrough. For example, the reinforcing piece which is formed of two superposed transparent synthetic resin films having different melting points and is adapted to be applied fast to a fastener tape by melting that of the two films having a lower melting point as disclosed in Japanese Utility Model Publication No. (hereinafter referred to briefly as "JUM-B-") 44-25,843 and the lateral application tape which is formed by superposing on one side of a transparent film of nylon 6 or nylon 66 a transparent polyester copolymer film having a melting point in the range of 80 to 200.degree. so as to show the color of the base fabric of the fastener tape therethrough as disclosed in published Japanese Patent Application, KOKAI (Early Publication) No. (hereinafter referred to briefly as "JP-A-") 62-149,780 have been known to the art.
Also JP-A-08-299,033 discloses a reinforcing tape which has a transparent elastomer film used for the obverse surface layer and an adhesive layer superposed on the reverse surface thereof and U.S. Pat. No. 3,490,970 discloses a method for reinforcing the end portions of fastener tapes by causing a wire mesh of metal or synthetic resin to adhere to at least one face of each of the fastener tapes by the use of a thermoplastic resin under application of heat and pressure.
Since the reinforcing tapes formed of two layers of synthetic resin film as are disclosed in JUM-B-44-25,843 and JP-A-62-149,780 mentioned above have the component layers thereof invariably formed of film, they are at a disadvantage in being deficient in torsional strength and transverse tensile strength (laterally drawing strength). Since they are hard from the material point of view, they cannot be easily shaped by bending in conformity with the shape of the core portion of the fastener tape and, for this reason, the core portion of the fastener tape is not easily formed accurately in contour thereof. Further, these reinforcing tapes have the problem that when they are repeatedly bent, the bent lines thereof ultimately cause whitening possibly to the extent of jeopardizing the appearance of the reinforcing tapes.
The reinforcing tape disclosed in JP-A-08-299,033 forms the surface layer with an elastomer film and, therefore, is at an advantage in exhibiting due flexibility and consequently allowing itself to be easily bent in conformity with the contour of the core portion of the fastener tape. Since the component layers of this reinforcing tape are formed of film, however, the reinforcing tape has room for further improvement in terms of torsional strength and transverse tensile strength.
The reinforcing tape disclosed in U.S. Pat. No. 3,490,970 which resorts to the combination of a thermoplastic resin with a wire mesh gains in rigidity and secures satisfactory strength owing to the wire mesh. It nevertheless is at a disadvantage in assuming a rigid constituent as a whole, suffering from insufficiency in flexibility, and consequently incurring difficulty in being shaped by the kind of bending which is mentioned above.